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Ammo for your 3Gun AR15

As you progress in the sport of 3Gun you no doubt want to increase your effectiveness at long range targets often presented in 3Gun Major Matches. In this article I will detail how to evaluate and select an appropriate load for your 3Gun rifle, how to sight it in and what factors are important for success. AR-15

First, Let’s Define Some parameters: Generally speaking 55gn bulk ammo is often not quite accurate enough, doesn’t carry enough energy and gets disturbed by the wind too much to be the go to round for long distance engagements. I typically recommend 200yards and in for 55gr 223 rounds for 3gun.

These loads are more than adequate for bay style stages, plate racks and mid-distance targets. Past 200 yards a heavier more precise projectile is desirable. The heavier projectiles will carry more inertia thereby indicating better when striking steel and will buck the wind better at further distances. The typical projectile weight range for a 223 cartridge for longer distance engagements is 65 to 77 grains depending on the manufacturer you select.

Now that we have narrowed down the relative projectile size, we need to select a cartridge to test and define the parameters of acceptable.

Here is the list of equipment I recommend for this evaluation:

  1. Your primary 3Gun Rifle with a higher power optic 10x-12x or larger for test purposes
  2. Chronograph that captures average velocity and standard deviation or a program to calculate.
  3. Ballistic Calculator APP such as IStrelok
  4. Spotting Scope
  5. Bipod, bags or stable shooting structure for repeatable shots.

Evaluation Process:

Check shot grouping of ammo being evaluated at 100, 200 and 300 yards. I start with accuracy, because if the round isn’t accurate it doesn’t matter about velocity, standard deviation or reticle matchup.

a. Goal is to maintain sub MOA groups (1in @100, 2in @200 etc) as a minimum requirement. I much prefer a ½ MOA round as it will increase your effectiveness.

Capture and record velocity information, average and standard deviation for at least 10 rounds to begin with, more later if necessary.

Plug your Average Velocity information into the ISTRELOK APP. Here is the point where the real evaluation comes in.

Here is where the evaluation begins:

Let’s say for example your ammo provides an average velocity of 2800fps. With a min of 2720 and a max of 2820. Input your average velocity along with BC, Zeroing distance, scope height etc. and review this table against your minimum and maximum velocities. This round @2720fps for example, would drop an additional 4in at 400 yards over your average. So, in practical application a dead center hold on your 400 yard subtension would result in a low miss on an 8in target at that distance. The lesson here is that a small standard deviation is desirable to create predictable loads. This is where manufacturing quality comes into play. The type of powder, powder metering, the primer seating operation and bullet crimp operation all factor into the quality of that ammo and can increase or decrease quality.